First of all part of the lyrics are wrong, He says "Found a hole and fell inside myself", not "fill inside myself", I would fix it but the correction link is greyed out. Sometimes we get so lost in the sins we've committed that we do kind of fall into ourselves--in the sense that our lives become prisons because the disease of sin has us trapped. We make excuses not only because we don't want to face it but because we don't yet realize that only with Jesus' help can we break out of it--break free.